Brush holder



July 22. 1924. 1,502,139

- R. w. ELLIOTT ET AL BRUSH HOLDER Filed July 13. 1921 2 Shana-Sh; 1

July 22, 1924. 1,502,139

I R. w. ELLIOTT ET AL BRUSH HOLDER Filed July 13. 1921 2 Sheets-Sheet 2 Patented July 22, 1924.

UNITED STATES 1,502,139 PATENT OFFICE.

ROBERT W. ELLIOTT, WARREN A. JOHNSTON, AND LEWIS J. BUERKLE, 0F DAYTON, OHIO, ASSIGNORS TO THE DAYTON ENGINEERING LABORATORIES COMPANY, OF DAYTON, 01110, A CORPORATION OF OHIO.

BRUSH HOLDER.

Application filed July 13,

To all whom it may concern:

Be it known that we, Roennr W. ELLIOTT, WVARREN A. JOHNSTON, and Lnwrs J. Bone KLE, citizens of the United States of America, residing at Dayton, county of Montgomery, State of Ohio, have invented certain new and useful Improvements in Brush Holders, of which the following is a full, clear, and exact description.

This invention relates to improvements in brush supporting devices for electric machines having commutators.

It is among the objects of the present invention to eliminate brush squeaks or any other undue noises caused by the brushes.

A further object is to provide a brush structure that will cause certain portions of the contacting surface of the brush to engage with the commutator at different speedsthereof.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of'the present inven tion is'clearly shown.

In the drawings, Fig. 1 is a side elevation of the brush and its supporting elements.

Fig. 2 is a top plan view of the brush and brush holder.

Figure 3 is a view similar to Fig. 1 but showing the different positions of the brush when the spring plate support is distorted.

Fig. 4 is an end view of the brush support, the dotted lines showing the brush in its displaced positions, due to an imperfect commutator.

Fig. 5 is an end view of an electric machine with the brushes shown in relative positions. r

- Fig. 6 is an enlarged view of the device showing the toe or front edge of the'brush engaging with the commutator.

Fig. 7 is a. view similar to Fig. 6 but showing the middle of the brush engaging with the commutator, and V Fig. 8 is another view similar to Fig. 6 showing the heel or rear edge of the brush engaging the commutator.

Referring to the drawings, the numeral 20 designates a supporting arm, having ears 21 and 22 provided with holes through which the fulcrum pin '23, carried by the plate ficient operation of the machine.

1921. Serial No. 484,426.

2 1, is adapted to project, the pin forming a pivotal support for the arm 20.

Interposed between the ears 21 and 22 and secured to the supporting arm 20 is the spring plate 25 which is provided with an angular portion 26 to which is secured the brush 27 by means of screws 28 and nut 29. The arm 20 is provided with an extended portion 30 lying in alinement with and adjacent to the spring plate 25. This extended portion 30 has a hump 31 provided with a screw threaded hole 32 to which the lead wire is adapted to be screwed.

Another projection 33 extending from the ear 22 has a hook portion 34; against which one end of the coil spring 35 abuts while the opposite end of the spring is anchored on a stud 36 carried by the plate 24. This spring tends to hold the. brush 27 against the commutator 37.

Referring; to Fig. 3 it may be seen that the brush element 27 may be moved into different positions, as shown in dotted lines, due to the yieldability of the spring plate 25 on which the brush is mounted. This spring plate 25 will not only allow movement of the brush in this direction, which may be termed the commutator peripheral direction, but also as shown in Fig. i b the dotted lines which might be termed the commutator longitudinal direction.

The flexing properties of the flat plate or spring 25 depend chiefly on the metal used therein and the size of the spring. The plate lies in a. plane tangential to the commutator. Relatively stiff springs yield less to the frictional drag on the brush and re- .duce the rolling action of the brush end on the commutator.

In the commercial production of electric machines including commutators and brushes, certain imperfections in workmanship will occur that will tend to cause imperfect contact bet een the said commuta tors and brushes, resulting in. undesirable squeaks and noises. This condition will also cause undue sparking and poor commutation, thereby greatly affecting the ef- However in the present structure, if any imperfections in workmanship occur, the brush will still be held in substantially perfect contact with the commutator due to the yieldability of its spring carrier plate 25 and the action of the spring 35 to force the brush into good engagement with its commutator.

In operating commutators in electric ma chines under certain circumstances it has been found that due to heat the commutator has become distorted, thereby causing poor engagement of the brushes, affecting commutation and causing squeaky noises. In using the present brush structure with faulty commutators it has been found by experiment that the yielding brush mounting together with the effect of the tension spring 35 will tend to cause the brush to ride evenly on the commutator thus substantially overcoming the ill effects of commutator distortion and providing good commutation and eliminating noises. I

It is also well known in the art that the use of a very narrow brush, or, more specifically, a brush slightly wider than the insulation "between the commutator bars, is desirable in order to obtain good commutation and efficient machine operation. In the present invention the effect of a narrow brush is obtained by the use of a comparat'ively wide brush in the following man.- ner. The brush 27 and its component supporting elements are so positioned that when the machine is idleonly the toe or front portion of the brush marked A n Figs. '6, "Z, and '8 engages with the commutator. The middle and heel portions marked B and C respectively do not engage with the commutator. This provides a narrow brush -contact while using -a comparatively wide and mechanlcally strong brush.

The surface A will ride on the commutator when it is not .in motion and during a certain range of slow rotation of the commutator. As soon as the commutator is driven at a higher rate, or what might be termed a normal operating speed, the frictional drag or pull of the commutator on the brush will tend to move the said brush in the direction of commutator rotation, "indicated by the arrow, against the action of the spring plate '25 which will now be distorted. This rocking or moving of the brushin the said direction will tend to cause its intermediate end surface or zone 'B to ride on the commutator, thus again providing only a comparatively narrow operative brush surface.

As the speed of the commutator increases above normal, the brush will be drawn furtheriin the direction of commutator rotation thus causing the brush to ride on its heel or C surface as shown in Fig. 8. Due to the action of the spring plate 25,

the brush will assume its previous positions as the speed of rotation of the commutator is reduced.

IVhile the form of mechanism herein shown and described constitutes a preferred form of embodiment of the invention, it is to be understood that other forms might be adopted, all coming Within the scope of the claims which follow.

What we claim is as follows:

1. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of means for holding said brush in engagement with the commutator so that different portions thereof will engage said com-mutator under varying speeds.

2. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of means for yieldingly maintaining the brush in engagement with the commutator while at the same time permitting different portions of the brush to engage said commutator under varying speeds.

3. In a dynamo :electric machine the combination with the commutator thereof and a brush for engaging the commutator; of means for yieldingly maintaining only the toe portion-of the brush in engagement with y the commutator while said commutator is rotating at relatively low speeds.

4'. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of means for yieldingly maintaining only the middle portion of the brush in engagement with the commutator while said commutator is rotating at relatively normal speed.

5. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of means for yieldingly maintaining only the heel portion of the brush in engagement with the commutator while said commutator is'rotating at relatively "high speed.

6. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of a yieldab-l'e support for the brush, permitting the engaging surface thereof to rock sidewise upon the commutator when said commutator is in mction; and means for yield- 'ingly urging said support toward the commutator.

7 In a dynamo electric machine the combinationwith the commutator thereof "and a brush for engaging the commutator; -of a yieldab'le support for the brush, permitting the engaging su r-face thereof to rock edgewise upon the commutator when said com- 8. In a "dynamo electric "machine the combination with the commatatorthereorf and a brush for engaging the commutator; of a yieldable support for the brush, permitting the engaging surface thereof to rock sidewise and edgewise upon the commutator when said commutator is in motion; and means for yieldingly urging said support toward the commutator.

9. In a dynamo electric machine the combination with the commutator thereof and a brush for engaging the commutator; of a leaf-spring adapted to carry said brush; a pivotal support having one end of the leaf spring attached thereto; and a spring associated with said support for yieldingly urging the leaf-spring toward the commutator for causing the brush to engage therewith.

10. In a dynamo electric machine, the combination of a support; a commutator rotatably mounted thereon; a brush having endwise engagement with the commutator; and means for supporting said brush, comprising a flexible flat member pivotally mounted on the support with a fiat face thereof toward the commutator, means yieldingly urging the free end of the member toward the commutator, and means for 2 securing the brush to the free end of the member.

11. In a dynamo electric machine, the combination of a field frame; a rotor mounted therein; a cylindrical commutator on one end of the armature; a brush having endwise engagement with the commutator; a flexible flat member supporting the brush and lying in a direction substantially tangential to the commutator and having one of its ends pivotally mounted on the field frame, the free end being bent out of the said tangential direction and fastened to the brush; and means for yieldingly urging the flat member toward the commutator.

In testimony whereof we hereto aflix our signatures.

ROBERT XV. ELLIOTT. lVARREN A. JOHNSTON. LEVIS J. BUERKLE. Witnesses:

H. E. SoLLENBnRenR, IRVIN A. GREENWALD. 

